Investigation of formation kinetics of polyurethanes based on different types of diisocyanates and castor oil

Abstract

The formation of polyurethanes based on vegetable oils is very complex and thus, for industrial production of these materials, it is important to determine the optimal temperature for polymerisation and to finally obtain materials with the proper mechanical properties. The goal of this work was to assess the kinetics of catalysed and noncatalysed reactions for polyurethanes based on castor oil as the polyol component and different types of diisocyanates. Due to the presence of hydroxyl groups on ricinoleic acid, castor oil is suitable for polyurethane preparation. Differential scanning calorimetry has been employed to study the poly-urethane formation reaction using the Ozawa isoconversion method. It was estimated that the catalyst addition decreases the activation energy. The highest reduction of activation energy was observed for the reactive systems with hexa-methylene diisocyanate. The validity of the obtained kinetic model was examined by FTIR spectroscopy following the absorption of reactive groups. The obtained results of mechanical characteristics of the polyuretahane networks (with different NCO/OH ratio) confirmed that the applied method could be used for prediction of optimal reaction conditions in polyurethane networks synthesis.